WASHINGTON. Scientists say they have finally identified the cause of a devastating epidemic that has killed more than 5 billion sea stars along the Pacific coast of North America since 2013.
The outbreak of sea star wasting disease, which continues today, has affected more than 20 species from Mexico to Alaska. The hardest hit has been the sunflower sea star, which lost about 90 percent of its population in the first five years.
According to a study published Monday in Nature Ecology and Evolution, the culprit is a bacterium called Vibrio pectenicida, which has also been known to infect shellfish. Researchers detected it in the coelomic fluid, the liquid surrounding the organs of sea stars after years of false leads and challenges in tracing the source.
“It’s really quite gruesome,” said marine disease ecologist Alyssa Gehman of the Hakai Institute in British Columbia, Canada, one of the study’s authors. She explained that while healthy sea stars have puffy, straight arms, the disease causes lesions and eventually leads to arms falling off.
Early investigations suggested a virus might be responsible, but scientists later discovered the suspected densovirus is a normal resident in healthy sea stars. The breakthrough came when researchers analyzed the coelomic fluid of living specimens, finding the bacterial infection that had gone undetected in earlier studies of dead tissue.
Marine microbiologist Rebecca Vega Thurber of the University of California, Santa Barbara, who was not involved in the study, called the findings “a long-standing question solved about a very serious disease in the ocean.”
With the cause now identified, scientists hope to protect remaining populations by testing for healthy individuals, breeding them in captivity, and possibly reintroducing them to affected areas. They may also explore whether some populations have natural immunity and if treatments such as probiotics could help boost resistance to the disease.
